During laparoscopic surgery it is often required to shift the spatial placement of the endoscope in order to present the surgeon with an optimal view. Conventional laparoscopic surgery makes use of either human assistants who manually shift the instrumentation or alternatively of robotic automated assistants. Automated assistants utilize interfaces that enable the surgeon to direct the mechanical movement of the assistant, achieving a shift in the camera view. U.S. Pat. No. 6,714,841 discloses an automated camera endoscope in which the surgeon is fitted with a head mounted light source that transmits his head movements to a sensor, forming an interface that converts said movements to directions for the mechanical movement of the automated assistant. Alternative automated assistants incorporate a voice operated interface, a directional key interface, or other navigational interfaces. The main disadvantage of the above interfaces is that they are based on cumbersome operations for starting and stopping movement directions that requires the surgeon's constant attention.
An article titled “A method for estimating the real time Positions of a moving object in wireless telemetry applications using RF sensors” by K. Arshak was recently published. The article relates to locating a transmitting object using multiple receiving antenna sensors located at various place surrounding the transmitting device. The receiver antennas are assumed to be omni directional and the location of the transmitter is achieved through distance estimation (i.e., triangulation) from each of the receiving antenna.
The distance from the transmitter is estimated by measuring the received signal strength (RSS) of the received signal:RSS=PT−PL(d0)−10η log10(d/d0)+Xσ,calculated in decibel, PT is the transmitted power, PL(d0) is the path loss for a reference distance d0, η is the pass loss exponent, d is the distance between the transmitter and the receiver and Xσ is a Gaussian random variable.
Therefore, the signal received is proportional to transmit power (PT), the η power of distance to the transmitter, normally in free space η=2, if all is known except the distance, it can be resolved from the above mentioned equation, a distance can be calculated from each of the receiving antenna
The object (transmitter) location is at the intersection of spheres with every distance which is the respective sphere radius (i.e., Triangulation).
Arshak states in the article that other method such as time of arrival, time differences of arrival and angle of arrival are not feasible due to dense multipath environment. Yet more, if the transmit power is unknown, unstable or inaccurate; or if the propagation factor is unknown then Arshak's method won't be valid.
Therefore there is still a long felt need for a method which will enable the relative position of the transmitter (and thus the medical instrument).
Research has suggested that these systems divert the surgeons focus from the major task at hand. Therefore technologies based on various kinds of positioning systems have been developed to simplify interfacing control. These technologies still fail to address another complicating interface aspect of laparoscopic surgery, however, as they do not allow the surgeon to signal both to the automated assistant and to surgical colleagues on which surgical instrument his attention is focused.
Thus, there is a long-felt need for a device that would allow the surgeon to identify to the laparoscopic computing system as well as to surgical colleagues to which surgical instrument attention is to be directed, thereby directing the view provided by the endoscope to the selected area of interest.